Fire and Emergency New Zealand Hastings senior station officer Michael Manning said two fire appliances and crews spent more than two hours at the blaze.
"Our crews located a woman inside the structure, she was removed and was treated by firefighters and paramedics.
"She suffered life-threatening injuries as a result of the fire."
The fire started in a bedroom and was able to be confined to that room, however other parts of the house were smoke and fire damaged, he said.
Fire investigators had not yet determined the cause of the blaze but had been examining the scene.
Given the fact that a person had suffered life-threatening injuries the incident was also referred to police, Mr Manning said.
A Hawke's Bay Hospital spokesperson said a woman in her 30s remained in a critical condition last night.
A Fire and Emergency New Zealand spokesperson said Porangahau Volunteer Fire Brigade was called to a kitchen fire on Keppel St, Porangahau, at 4.44pm.
A St John Ambulance spokesperson said one person was transported by ambulance to Hawke's Bay Hospital in a moderate condition.
Anyone with information on the Kauri Pl fire is asked to call Hastings Police on 06 831 0700 or Crimestoppers anonymously on 0800 555 111.
